<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>来回拖放</title>
  <style type="text/css">
    #div1, #div2{
      float: left;
      width: 198px;
      height: 66px;
      margin: 10px;
      padding: 10px;
      border: 1px solid #aaaaaa;
    }
  </style>
  <script type="text/javascript">
    function allowDrop(ev)
    {
      ev.preventDefault();
    }
    function drag(ev)
    {
        ev.dataTransfer.setData("Text",ev.target.id);
    }
    function drop(ev)
    {
        ev.preventDefault();
        var data = ev.dataTransfer.getData("Text");
        ev.target.appendChild(document.getElementById(data));
    }
  </script>
</head>
<body>

<div id="div1" ondrop="drop(event)" ondragover="allowDrop(event)">
    <img src="img/eg_dragdrop_w3school.gif" draggable="true" ondragstart="drag(event)" id="drag1">
</div>
<div id="div2" ondrop="drop(event)" ondragover="allowDrop(event)"></div>

</body>
</html>